我们在常用的电商或者旅游APP中，例如美团，手机淘宝等等，都能够看的到有那种下拉式的二级列表菜单。具体如图所示：
(应大家需要提供下载地址：)有人说受教了，可有人反应下载不下来！下来不知道怎么打开！我惊了，我自己再去下载，然后导入完全没有问题。我的环境是ubuntu14.04下的Eclipse ADT环境，谷歌标准环境。
上面两张图就是美团的一个二级列表菜单的一个展示。我相信很多人都想开发一个跟它一样的功能放到自己的APP中。好，接下来我们就开始动手，解决它。
1，结构分析
首先，我们给出这个下来菜单需要的组建。我们用线框图来分析。
1）如上图所示，最外围的是一个Activity，顶部包含了一个View的容器，这个容器主要是装载ToggleButton来实现诸如美团里面的“美食，全城，理我最近，刷选”这一行。这一行一点就会弹出对应的下来菜单。
2）下拉菜单是如何实现的呢？，这里我们利用了PopupWindow来实现这一弹出式窗口。然后我们在弹出式窗口里面再定义我们的下来列表项，是单列还是二级菜单，都是由里面来定。
3）不同的菜单，需要一级或者需要二级，在这里根据我的需求而变动。我们在PopupWindow上面加一个自定义的LeftView，或者是MiddleView，RightView。主要是一个ToggleButton，你弹出一个窗口，你就定制一个窗口。
3）视图里面嵌入ListView，就形成了列表项。
好分析就到上面为止，接下来我们一步步的说明实现。
2，项目结构
本项目的项目结构如图所示：
1） Adapter。适配器，主要是为ListView提供数据适配的。
2）MainActivity。主活动页面。
3）ExpandTabView。本项目的核心类，它包含ToggleButton容器和PopupWindow，是控制弹出窗口的核心类。
4）ViewLeft,ViewMiddle,ViewRight。是弹出里面嵌套的类，实现不同的列表菜单。
3，MainActivity
承载所有元素。看代码比看文字实在。
package com.example.expandtabview;import java.util.ArrayList;import android.app.Activity;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.Toast;import com.example.view.ExpandTabView;import com.example.view.ViewLeft;import com.example.view.ViewMiddle;import com.example.view.ViewRight;public class MainActivity extends Activity { private static final String TAG = "MainActivity"; private ExpandTabView expandTabView; private ArrayList mViewArray = new ArrayList (); private ViewLeft viewLeft; private ViewMiddle viewMiddle; private ViewRight viewRight; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); initVaule(); initListener(); } private void initView() { Log.d(TAG,"initView"); expandTabView = (ExpandTabView) findViewById(R.id.expandtab_view); viewLeft = new ViewLeft(this); viewMiddle = new ViewMiddle(this); viewRight = new ViewRight(this); } private void initVaule() { Log.d(TAG,"initValue"); mViewArray.add(viewLeft); mViewArray.add(viewMiddle); mViewArray.add(viewRight); ArrayList mTextArray = new ArrayList (); mTextArray.add("距离"); mTextArray.add("区域"); mTextArray.add("距离"); expandTabView.setValue(mTextArray, mViewArray);//将三个下拉列表设置进去 expandTabView.setTitle(viewLeft.getShowText(), 0); expandTabView.setTitle(viewMiddle.getShowText(), 1); expandTabView.setTitle(viewRight.getShowText(), 2); } private void initListener() { Log.d(TAG,"initListener"); viewLeft.setOnSelectListener(new ViewLeft.OnSelectListener() { @Override public void getValue(String distance, String showText) { Log.d("ViewLeft", "OnSelectListener, getValue"); onRefresh(viewLeft, showText); } }); viewMiddle.setOnSelectListener(new ViewMiddle.OnSelectListener() { @Override public void getValue(String showText) { Log.d("ViewMiddle","OnSelectListener, getValue"); onRefresh(viewMiddle,showText); } }); viewRight.setOnSelectListener(new ViewRight.OnSelectListener() { @Override public void getValue(String distance, String showText) { Log.d("ViewRight","OnSelectListener, getValue"); onRefresh(viewRight, showText); } }); } private void onRefresh(View view, String showText) { Log.d(TAG,"onRefresh,view:"+view+",showText:"+showText); expandTabView.onPressBack(); int position = getPositon(view); if (position >= 0 && !expandTabView.getTitle(position).equals(showText)) { expandTabView.setTitle(showText, position); } Toast.makeText(MainActivity.this, showText, Toast.LENGTH_SHORT).show(); } private int getPositon(View tView) { Log.d(TAG,"getPosition"); for (int i = 0; i < mViewArray.size(); i++) { if (mViewArray.get(i) == tView) { return i; } } return -1; } @Override public void onBackPressed() { if (!expandTabView.onPressBack()) { finish(); } }} 4 ，ExpandTabView
最主要就是如何处理当我们点击这些ToggleButton的时候要弹出或者收起这些PopupWindow。
package com.example.view;import java.util.ArrayList;import com.example.expandtabview.R;import android.app.Activity;import android.content.Context;import android.util.AttributeSet;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.widget.LinearLayout;import android.widget.PopupWindow;import android.widget.PopupWindow.OnDismissListener;import android.widget.RelativeLayout;import android.widget.TextView;import android.widget.ToggleButton;/** * 菜单控件头部，封装了下拉动画，动态生成头部按钮个数 * * @author zengjinlong */public class ExpandTabView extends LinearLayout implements OnDismissListener { private static final String TAG = "ExpandTabView"; private ToggleButton selectedButton; private ArrayList mTextArray = new ArrayList (); private ArrayList mViewArray = new ArrayList (); private ArrayList mToggleButton = new ArrayList (); private Context mContext; private final int SMALL = 0; private int displayWidth; private int displayHeight; private PopupWindow popupWindow; private int selectPosition; public ExpandTabView(Context context) { super(context); init(context); } public ExpandTabView(Context context, AttributeSet attrs) { super(context, attrs); init(context); } /** * 根据选择的位置设置tabitem显示的值 */ public void setTitle(String valueText, int position) { if (position < mToggleButton.size()) { mToggleButton.get(position).setText(valueText); } } public void setTitle(String title){ } /** * 根据选择的位置获取tabitem显示的值 */ public String getTitle(int position) { if (position < mToggleButton.size() && mToggleButton.get(position).getText() != null) { return mToggleButton.get(position).getText().toString(); } return ""; } /** * 设置tabitem的个数和初始值 * @param textArray 标题数组 * @param viewArray 控件数组 */ public void setValue(ArrayList textArray, ArrayList viewArray) { if (mContext == null) { return; } LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE); Log.d(TAG,"setValue"); mTextArray = textArray; for (int i = 0; i < viewArray.size(); i++) { final RelativeLayout r = new RelativeLayout(mContext); int maxHeight = (int) (displayHeight * 0.7); RelativeLayout.LayoutParams rl = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, maxHeight); rl.leftMargin = 10; rl.rightMargin = 10; r.addView(viewArray.get(i), rl); mViewArray.add(r); r.setTag(SMALL); ToggleButton tButton = (ToggleButton) inflater.inflate(R.layout.toggle_button, this, false); addView(tButton); View line = new TextView(mContext); line.setBackgroundResource(R.drawable.choosebar_line); if (i < viewArray.size() - 1) { LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(2, LinearLayout.LayoutParams.MATCH_PARENT); addView(line, lp); } mToggleButton.add(tButton); tButton.setTag(i); tButton.setText(mTextArray.get(i)); r.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Log.d("RelativeLayout","view:"+v); onPressBack(); } }); r.setBackgroundColor(mContext.getResources().getColor(R.color.popup_main_background)); tButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View view) { Log.d("tButton","setOnClickListener(l)"); // initPopupWindow(); ToggleButton tButton = (ToggleButton) view; if (selectedButton != null && selectedButton != tButton) { selectedButton.setChecked(false); } selectedButton = tButton; selectPosition = (Integer) selectedButton.getTag(); startAnimation(); if (mOnButtonClickListener != null && tButton.isChecked()) { mOnButtonClickListener.onClick(selectPosition); } } }); }// for.. } private void startAnimation() { Log.d(TAG,"startAnimation"); if (popupWindow == null) { Log.d(TAG,"startAnimation(),new popupWindow now"); popupWindow = new PopupWindow(mViewArray.get(selectPosition), displayWidth, displayHeight); popupWindow.setAnimationStyle(R.style.PopupWindowAnimation); popupWindow.setFocusable(false); popupWindow.setOutsideTouchable(true); } Log.d(TAG,"startAnimation(),selectedButton:"+selectedButton+",isChecked:"+selectedButton.isChecked()+ ",popupWindow.isShowing:"+popupWindow.isShowing()); if (selectedButton.isChecked()) { if (!popupWindow.isShowing()) { showPopup(selectPosition); } else { popupWindow.setOnDismissListener(this); popupWindow.dismiss(); hideView(); } } else { if (popupWindow.isShowing()) { popupWindow.dismiss(); hideView(); } } } private void showPopup(int position) { View tView = mViewArray.get(selectPosition).getChildAt(0); if (tView instanceof ViewBaseAction) { ViewBaseAction f = (ViewBaseAction) tView; f.show(); } if (popupWindow.getContentView() != mViewArray.get(position)) { popupWindow.setContentView(mViewArray.get(position)); } popupWindow.showAsDropDown(this, 0, 0); } /** * 如果菜单成展开状态，则让菜单收回去 */ public boolean onPressBack() { Log.d(TAG,"onPressBack"); if (popupWindow != null && popupWindow.isShowing()) { popupWindow.dismiss(); hideView(); if (selectedButton != null) { selectedButton.setChecked(false); } return true; } else { return false; } } private void hideView() { Log.d(TAG, "hide()"); View tView = mViewArray.get(selectPosition).getChildAt(0); if (tView instanceof ViewBaseAction) { ViewBaseAction f = (ViewBaseAction) tView; f.hide(); } } private void init(Context context) { mContext = context; displayWidth = ((Activity) mContext).getWindowManager().getDefaultDisplay().getWidth(); displayHeight = ((Activity) mContext).getWindowManager().getDefaultDisplay().getHeight(); setOrientation(LinearLayout.HORIZONTAL); } @Override public void onDismiss() { Log.d(TAG,"onDismiss,selectPosition:"+selectPosition); showPopup(selectPosition); popupWindow.setOnDismissListener(null); } private OnButtonClickListener mOnButtonClickListener; /** * 设置tabitem的点击监听事件 */ public void setOnButtonClickListener(OnButtonClickListener l) { mOnButtonClickListener = l; } /** * 自定义tabitem点击回调接口 */ public interface OnButtonClickListener { public void onClick(int selectPosition); }} 5，ViewLeft
其中的一个示例，其他两个就不列举了
package com.example.view;import com.example.adapter.TextAdapter;import com.example.expandtabview.R;import android.content.Context;import android.util.AttributeSet;import android.view.LayoutInflater;import android.view.View;import android.widget.ListView;import android.widget.RelativeLayout;import android.widget.Toast;public class ViewLeft extends RelativeLayout implements ViewBaseAction{ private static final String TAG = "ViewLeft"; private ListView mListView; private final String[] items = new String[] { "item1", "item2", "item3", "item4", "item5", "item6" };//显示字段 private final String[] itemsVaule = new String[] { "1", "2", "3", "4", "5", "6" };//隐藏id private OnSelectListener mOnSelectListener; private TextAdapter adapter; private String mDistance; private String showText = "item1"; private Context mContext; public String getShowText() { return showText; } public ViewLeft(Context context) { super(context); init(context); } public ViewLeft(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(context); } public ViewLeft(Context context, AttributeSet attrs) { super(context, attrs); init(context); } private void init(Context context) { mContext = context; LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); inflater.inflate(R.layout.view_distance, this, true); setBackgroundDrawable(getResources().getDrawable(R.drawable.choosearea_bg_mid)); mListView = (ListView) findViewById(R.id.listView); adapter = new TextAdapter(context, items, R.drawable.choose_item_right, R.drawable.choose_eara_item_selector); adapter.setTextSize(17); if (mDistance != null) { for (int i = 0; i < itemsVaule.length; i++) { if (itemsVaule[i].equals(mDistance)) { adapter.setSelectedPositionNoNotify(i); showText = items[i]; break; } } } mListView.setAdapter(adapter); adapter.setOnItemClickListener(new TextAdapter.OnItemClickListener() { @Override public void onItemClick(View view, int position) { if (mOnSelectListener != null) { showText = items[position]; mOnSelectListener.getValue(itemsVaule[position], items[position]); } } }); } public void setOnSelectListener(OnSelectListener onSelectListener) { mOnSelectListener = onSelectListener; } public interface OnSelectListener { public void getValue(String distance, String showText); } @Override public void hide() { } @Override public void show() { }} 6，效果图
好，今天就到这里。。希望有用。